Dredging bucket having a reinforced edge

ABSTRACT

A reinforced dredging bucket of hardened manganese steel has an edge formed from a plurality of successively alternating, integrally cast first and second regions. The first regions consist of the main bucket metal formed from a composition consisting of 0.5 to 2 % carbon; 6 to 30 % manganese; and up to 3 % silicon, chromium, molybdenum, and vanadium, singly or in combination, the rest being iron and steel impurities. The second regions, which may project beyond the first regions to form teeth, consist of a wear-resistant material formed from 1.2 to 4 % carbon; 15 to 30 % chromium; 0.2 to 10 % manganese; 0.1 to 5 % silicon; up to 10 % nickel; and up to 10 % of elements forming carbides and/or nitrides, the rest being iron and steel impurities.

United States Patent 1191 Leolien et al.

1451 July 29,1975

DREDGING BUCKET HAVING A REINFORCED EDGE lnventors: Bernd Kos Leoben;Alois Kubasa,

Mitterdorf, both of Austria Appl. No.: 414,092

2,132,373 10/1938 Bartholomew 76/101 A X 2,429,800 10/1947 Briggs 75/128A 2,706,696 4/1955 Payson.... 75/128 A X 2,709,132 5/1955 Giles 75/126 A3,113,861 12/1963 Norman..... 75/123 N 3,330,651 Younkin 75/123 NPrimary Examiner 'Clifford D. Crowder 57 ABSTRACT A reinforced dredgingbucket of hardened manganese [30}, Foreign Applicationrpriority D steelhals an edge formed"from afpluralitiy of sugcessive y aternatlng, mtegray cast irst an secon re- Nov. 24,1972 Austria 10006/72 gions The firstregions consist of the main bucket metal formed from a compositionconsisting of 0.5 to [52] US. Cl 37/141 R, 29/1961, 29/213696; 2 carbon;6 to 30 manganese; and p to 3 Int Cl Eozf 9/28 823p 3/00 con, chromium,molybdenum, and vanadium, singly or Fie'ld "5 N B 128 A in combination,the rest being iron and steel impuri- 75/126 l 191 377141 ties. Thesecond regions, which may project beyond 141T 4 R the first regions toform teeth, consist of a wear- 76 01 resistant material formed from 1.2to 4 carbon; 15 to 30 chromium; 0.2 to 10 manganese; 0.1 to 5 silicon;up to 10 nickel; and up to 10 of elements [56] References Cited formingcarbides and/or nitrides, the rest being iron UNITED STATES PATENTS andSteel impurities. 1,310,528 7/1919 Hadfield 75/123 N 1,430,782 10/1922Attenborough et a1 37/141 R 2 Clams, 2 Drawmg Flgures l J l J l 1DREDGING BUCKET HAVING A REINFORCED EDGE The invention relates to adredging bucket cast in hard manganese steel with a wear-resistantworking edge, such buckets being adapted for use, for example, on aconveyor chain. In this specification, refers to percentage by weight.

As a rule dredging buckets which are made of wearresistant steels(consisting of 0.5 to 2 carbon; 8 to 30 manganese; and up to 3 silicon,chromium, molybdenum and vanadium, singly or in combination, the restbeing iron and impurities) are produced by casting in a mold. Thewearing edges of dredging buckets are exposed to frictional abrasion.The resulting worn portions are repaired by welding on wearresistantmaterials. The generally expected working life of a dredging bucket issome 5 years, with to welding repairs in that period for maintaining itsfunctional capacity.

The welding work requires prolonged immobilization of an entire conveyorchain, which is composed as a rule of 120 to 140 dredging buckets. Apartfrom the considerable cost of the welding metal such as wires, the workitself is time-consuming and expensive. Owing to the nature of thelining alloys that are normally employed, only a replacement layer ofthe same kind, or in the case of hard alloys just one or a few layers,can be produced in most cases. In addition, this necessitates holdingwelding experts in readiness right at the working site, in order tocarry out the necessary repairs then and there.

Proposals for reducing the conveyor laydown times to an economicallyacceptable minimum have been directed at exchanging complete buckets,and doing the welding work at one time on those that are in most need ofrepair. This again has occasioned increased costs of transportation andhas required very great capital outlay, since in practice almost everyconveyor chain with to 30 dredging buckets requires spare buckets, sothat the production time saved and the gain thus obtainedcounterbalanced each other.

The present invention is described below, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a view in elevation of an experimental man- Three. small steelanti-wear plates ll (FIG. 1) whose composition was 2.6 carbonand 5manganese were then placed by casting in one edge of an experimentalplate I of manganese steel whose composition was 1.2 carbon, 12manganese, and 1% silicon, and this edge was exposed to wear. Thecast-in antiwear plates II project about 10 mm from the edge of the hardmanganese steel plate I, and are spaced 35 mm apart. The test plate wasdriven at a peripheral speed of 3 in per second through a bed ofabrasive. Quartz sand interspered with basalt splinters was used as theabrasive. The initial duration of the test was four weeks. Visualinspection revealed that the anti-wear plates experienced practically nowear during this period, while the zones between the anti-wear platesexhibited slight erosion. This erosion is shown by hatchings V in FIG.1.

A subsequent test period of 6 weeks under the same test conditionssurprisingly revealed that the parts between the anti-wear platessuffered no further erosion. The anti-wear plates themselves displayedonly minor effects of wear and preserved a smooth polished condition.

A dredging bucket in accordance with the invention is shown in sectionin FIG. 2. The anti-wear teeth are cast into the edge zone VI which issubject to wear.

PREFERRED EMBODIMENT OF THE INVENTION The invention provides a dredgingbucket cast in hard manganese steel consisting of 0.5 to 2% carbon, 6 to30 manganese, up to 3 silicon, chromium, molybdenum, and vanadium, therest iron and impurities,

the invention consisting in that cast into the wearing edge of thedredging bucket are teeth of a material resistant to wear. The teethemployed here may consist of a wear-resisting steel consisting of 1.2 to4 carbon, 15 to 30 chromium, 0.2 to 10 maganese, 0.1 to 5 silicon, up to10 nickel, and up to 10 of elements forming carbides and nitrides, suchas tungsten, molybdenum, vanadium, tantalum, niobium, and titanium,joinly or separately, the rest being iron and impurities.

The spacing of theteeth may be between 5 and 150 mm according to thetype of stress encountered in service. It must, however, be borne inmind that if the spacing is too wide the erosion may become so deepganese steel plate one edge of which is provided with v wear resistantteeth; and

FIG. 2 is a fragmentary side elevation of a dredging bucket, parly insection.

EXPERIMENTATION Extensive experiments testing various types of steel forwear have shown that a steel containing 2.6 carbon, 25 chromium, and 5%manganese, the rest being iron and impurities normally found in steel,is ten times more resistant to wear than a steel with 1.2 carbon, l2manganese, and 1.5 chromium, the rest being iron and impurities.Unfortunately, however, casting tests have revealed that thefirst-mentioned type of steel is technically unsuitable for producingdredging buckets.

A further attempt at mounting small cast'pieces of this wear-resistantquality upon the base body by means of a mechanical bond had to beabandoned, because the joint would not stand up under the workingstresses encountered.

that the teeth lose their hold in the body of the bucket and fall out.As the wear experiment described above shows the most advantageousspacing a (FIG. 1) be-' I tween two teeth is fromv 30 to 60 mm inpractice.

Further experiments have shown that the wear resistance of the dredgingbuckets does not decrease if the teeth do not project from the workingedge.

Although the invention is illustrated and described with reference to aplurality of preferred embodiments thereof, it is to be expresslyunderstood that it is in no way limited to the disclosure of such aplurality of preferred embodiments, but is capable of numerousmodifications within the scope of the appended claims.

What is claimed is:

1. As an improved article of manufacture, a reinforced dredging bucketof hard manganese steel, the bucket having an edge formed from aplurality of successively alternating, integrally cast first and secondregions, each first region consisting by weight of 0.5 2 carbon, 6 30manganese, up to 3 of at least one element selected from the groupconsisting of silicon, chromium, molybdenum, and vanadium, theremainder' being iron and steel impurities, each second regionconsisting by weight of 1.2 4 carbon, 15 30 chromium, 0.2 to 10manganese, 0.1 5 silicon, up to nickel, up to 10 of at least one car 5bide-forming or nitride-forming element selected from the groupconsisting of tungsten, molybdenum, vanafirst regions to define teeth onthe edge of the bucket.

1. AS AN IMPROVED ARTICLE OF MANUFACTURE, A REINFORCED DREDGING BUCKETOF HARD MANGANESE STEEL, THE BUCKET HAVING AN EDGE FORMED FROM APLURALITY OF SUCCESSIVELY ALTERNATING, INTEGRALLY CAST FIRST AND SECONDREGIONS, EACH FIRST REGION CONSISTING BY WEIGHT OF 0.5-2% CARBON, 6-30%MANGANESE, UP TO 3% OF AT LEAST ONE ELEMENT SELECTED FROM THE GROUPCONSISTING OF SILICON, CHROMIUM, MOLYBDENUM, AND VANADIUM, THE REMAINDERBEING IRON AND STEEL IMPURITIES, EACH SECOND REGION CONSISTINGBY WEIGHTOF 1.2-4% CARBON, 15-30% CHROMIUM, 0.2 TO 10% MANGANESE, 0.1-5% SILICON,UP TO 10% NICKEL, UP TO 10% OF AT LEAST ONE CARBIDE-FORMING ORNITRIDE-FORMING ELEMENT SELECTED FROM THE GROUP CONSISTING OF TUNGSTEN,MOLYBDENUM, VANADIUM, TANTALUM, NIOBIUM, AND TITANIUM, THE REMAINDERBEING IRON AND STEEL IMPURITIES.
 2. The improved article as defined inclaim 1, in which the second regions extend outwardly beyond the firstregions to define teeth on the edge of the bucket.